On the effect of mutations in bovine or camel chymosin on the thermodynamics of binding κ-caseins

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Ansari, Samiul M. and Sørensen, Jesper and Schiøtt, Birgit and Palmer, David S. (2017) On the effect of mutations in bovine or camel chymosin on the thermodynamics of binding κ-caseins. Proteins: Structure, Function, and Bioinformatics. pp. 1-36. ISSN 0887-3585 (https://doi.org/10.1002/prot.25410)

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Abstract

Bovine and camel chymosins are aspartic proteases that are used in dairy food manufacturing. Both enzymes catalyse proteolysis of a milk protein, κ-casein, which helps to initiate milk coagulation. Surprisingly, camel chymosin shows a 70 % higher clotting activity than bovine chymosin for bovine milk, while exhibiting only 20 % of the unspecific proteolytic activity. By contrast, bovine chymosin is a poor coagulant for camel milk. Although both enzymes are marketed commercially, the disparity in their catalytic activity is not yet well understood at a molecular level, due in part to a lack of atomistic resolution data about the chymosin - κ-casein complexes. Here, we report computational alanine scanning calculations of all four chymosin - κ-casein complexes, allowing us to elucidate the influence that individual residues have on binding thermodynamics. Of the 12 sequence di erences in the binding sites of bovine and camel chymosin, eight are shown to be particularly important for understanding di erences in the binding thermodynamics (Asp112Glu, Lys221Val, Gln242Arg, Gln278Lys. Glu290Asp, His292Asn, Gln294Glu, and Lys295Leu. Residue in bovine chymosin written first). The relative binding free energies of single-point mutants of chymosin are calculated using the molecular mechanics three dimensional reference interaction site model (MM-3DRISM). Visualisation of the solvent density functions calculated by 3DRISM reveals the di erence in solvation of the binding sites of chymosin mutants.

ORCID iDs

Ansari, Samiul M. ORCID logoORCID: https://orcid.org/0000-0003-1066-1112, Sørensen, Jesper, Schiøtt, Birgit and Palmer, David S. ORCID logoORCID: https://orcid.org/0000-0003-4356-9144;
  • Item type:Article
    ID code:62184
    Dates:
    Date
    Event
    30 October 2017
    Published
    30 October 2017
    Published Online
    27 October 2017
    Accepted
    Notes:This is the peer reviewed version of the following article: Ansari, SM, Sørensen, J, Schiøtt, B & Palmer, DS 2017, 'On the effect of mutations in bovine or camel chymosin on the thermodynamics of binding κ-caseins' Proteins: Structure, Function, and Bioinformatics, pp. 1-36., which has been published in final form at https://doi.org/10.1002/prot.25410. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
    Subjects:Medicine
    Department:Faculty of Science > Pure and Applied Chemistry
    Depositing user: Pure Administrator
    Date deposited:31 Oct 2017 01:18
    Last modified:12 Dec 2024 05:51
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/62184
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